Vibratory catheterization apparatus and method of using



5 12&- 3 1:

March 18, 1969 c. A. BOYD 3,433,226

VIBRATORY CATHETERIZATION APPARATUS AND METHOD OF USING Filed July 21,1965 w n y 7 2o 22 et! I a INVENTOI? CHARLES A. BOYD ATTORNEYS.

.-.cludingscoronary atherosclerosis.

United States Patent 3,433,226 VIBRATORY CATHETERIZATION APPARATUS ANDMETHOD OF USING Charles A. Boyd, West Chester, Pa.,'assignor toAeroprojects Incorporated, West Chester, Pa., a corporation ofPennsylvania Filed July 21, 1965, Ser. No. 473,596 US. Cl. 128-305 Int.Cl. A61b 17/32; A6111 1/00; A6lm 25/00 Claims ABSTRACT OF THE DISCLOSUREThis invention relates to the use of ultrasonic energy for therapeuticpurposes, and more particularly to a therapeuticvmethod and apparatusfor such purposes as localization and yibratory treatment of irculatioyblocking ..L9 2i 1:@9 z inatieassiiiifi A 4; those occurring in varioustypes of a cl rosis in:

It has been suggested heretofore to use ultrasonic energy in treatingpatients having subdeltoid bursitis with the energy reportedly beingexternally applied through the a skin over the affected area via aliquid petrolatum coupling agent, using an intensity of preferably 0.5watt/ C1132:

ar 1d a maximum of 1.5 watts/cm The ul'fras'onic en e-rgy produces apowerful and deep micromassage, exerts localized thermal action, andincreases interacellular me tabolism; it causes exud-ates andprecipitates to be absorbed and tissue deposits to be broken up; itloosens tissue, relieves edema, decreases liypertonicity of the muscle,and produces a local analgesia causing an immediate relief of pain.(Page 73, The Indication and Contraindications for Ultrasonic Therapy inMedicine" by J. H. Aldes, in Ultrasound in Biology and Medicine,American Institute of Biological Sciences, Washington. DC, PublicationNo. 3, 1957) It is to be noted that in this bursitis experimentation,the externally applied ultrasonic energy was ineffective in 52. percentof the cases in decreasing or eliminating calcareous deposit. It hasalso been suggested (page 161, Ultrasonic Technology by Richard G.Goldman, New York: Reinhold Publishing Corp., 1962): r

It is interesting also to speculate on the possibility of inserting asmall transducer into the stomach or heart, which can then irradiategall stones or calcinations at close range with localized effect.

Moreover, at page l6l of the July-September 1964 3,433,226 Patented Mar.18 1969 issue (vol. 2) of Ultrasonics, in a Letter to the Editor, therewas reported an unsuccessful attempt to apply ultrasonic energy with theend object of emulsifying atherom atous material while leaving thestrong fibrous coat of the artery intact or re-boring atheromaobstructedarteries too small for conventional endarterectomy. Thus, postmortemspecimens of arteries affected by various degrees. of atheroma wereirradiated in water with ultrasound for at least 30 minute periods atfrequencies of 20 kc. and l mc. using 50 and 60 watts of power withpiezoelectric crystals, and also at 13 kc. using up to 100 watts ofpower with an industrial magnetostrictive transducer. There was noobvious effect whatever in the 13 kc. experiments, and the onlymacroscopic effect in the 20 kc. and 1 mc. experiments was co'agulationpartly due to "heat.

In other work, a commercial general-purpose apparatus (advertised toenable production of a widerange of effects in chemistry, biology,pharmacology, metallurgy, etc.) was impractical for blood vesseldecalcification. Touching a solid acoustical coupling member probe (partof an. ultrasonic apparatus having a design frequency of 20 kc.' and amaximum average output of watts) to atheromatous placques for 15-20seconds resulted in decimation of the placques; however, there wasshearing of the silver braze joint joining the probe to the remainder ofthe apparatus. Further experiments, with a catenoidal coupling .mem-berattached to the same basic apparatus, with an in--*- p'u't'to thetransducer of 9 watts (power level), readily cleared atheromatousmaterial from cadaver coronary vessels but, after one minute ofultrasonic energy application, tissue heating with destruction ofspecimens was often apparent.

The present invention overcomes the disadvantages of the prior art andindicates that tissue heating can be eliminated by using a hollowinternally cooled catheter. Excellent results on atheromatous aortatissue were 'obtained by passing ambient saline or a low molecularweight dextran solution through the probe. 0n cadaver coronary vessels,the atheromata was reduced to micron size particles using a power levelof 2.6 watts. Said par ticles can then be flushed away by use of adextran solution.

It is an object of .the present invention to provide novel apparatus andmethod for vibratory catheterization.

It is another object of the present invention to provide an ultrasoniccatheter for internal therapeutic purposes.

It is a further object of the present invention to provide a catheterfor decimation of atheromatous placques without hetiting tissues ordestruction of specimens.

Another object of the present invention is to provide apparatus forTreatment of coronary artery disease by u sonic coronary endarterectomy.

For the purpose of illustrating the invention there is shown in thedrawings a form which is presently preferred, it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalitie's shown.

FIGURE 1 is a sectional view of a catheter.

FIGURE 2 is a sectional view of the tip end of another embodiment.

FIGURE 3 is a sectional view of the tip end of another embodiment.

Referring to the drawings, wherein like reference characters refer tolike parts, there is shown'in FIGURE 1 an ultrasonic catheter generallydesignated as 10.

The catheterlg is essentially an ultrasonic transducercoupling systemcomprising an ult rasonic transducer 12, an acoustical coupling member14, another acoustical coupling member 16, and a third acousticalcoupling member 18 having an end face or tip 20. Member 18 is hollow andmetallurgically joined to merriber 14 in line with passageway 22.Passageway 23 intersects passageway 22. Conduit 24 is connected tomember 14 in passageway 23.

Catheter is designed to operate at a given frequency, which ispreferably a resonant frequency. Catheter 10 is preferably dimensionedto have an over-all physical length equivalent to an acoustical lengthof a whole number multiple of one-half wavelength in the material ofwhich it is made at the said frequency (see FIGURE 1 wherein "n"indicates a whole number). For efficient operation, there is an antinode(loop) area of the vibration at the end face 20.

Transducer 12 may be of the magnetostrictive type as shown and ofconventional construction comprising a half-wavelength long laminatedcore of nickel, nickel-iron alloy, or other magnetostrietive material,properly dimensioned to insure axial resonance with the frequency ofalternatlng current applied thereto by coil 1 -1 so as to cause it toincrease or decrease in length according to its coefiicient ofmagnetostriction. The detailed construction of a suitablemagnetostrietive transducer is well known to those skilled in the artand does not form a part of the present invention and, accordingly, nodescription of its construction will be made herein. It will beappreciated by those skilled in the art that in place of themagnetostrictive transducer 12 other known types of transducers may besubstituted; for example, an electrostrictive or piezoelectrictransducer made of bariuriftitar'iate, quartz crystals, lead zirconatetitanate, etc., may be utilized.

Transducer 12 is provided with an excitation coil '11 and a polarizingcoil 13. Excitation coil 11 is connected to a power supply(incorporating an amplifier, not shown, and oscillator, not shown)suitable for powering the transducer 12; such equipment is well known tothe art. The desirability of magnetically polarizing themagnetostrictive transducer 12 by means of polarizing coil 13, in orderfor the metal laminations in said transducer to efiiciently convert theapplied energy from excitation coil 11 into elastic vibratory energy, isalso readily understood by those skilled in the art. Low voltage directcurrent can be supplied to coil 13 by battery, rectifier, or other meanswell known to the art.

The aforesaid power supply system, in a typical example, is capable ofproducing electrical signals in the range of between about 60 cycles persecond and about 300,000 cycles per second. This frequency range issuitable for purposes of the present invention, including as it doesfrequencies in both the audible range (such as up to about 15,000 cyclesper second) and the ultrasonic range (generally above about 15,000cycles per second). A preferred frequency would be in the range of fromabout 3,000 to about 50,000 cycles per second with the optimum beingbetween about 14,000 to about 35,000 cycles per second. Normally, afrequency is chosen which will provide a suitable size of apparatus fora given application or set of applications, with the ultrasonic rangehaving the further advantage of inaudibility for operator comfort.

Thus, catheter transducer-coupling system 10 may be constructed tooperate at 28,000 cycles per second, for example. In an embodiment ofFIGURE 1, a 100 watt power supply was used to drive a transducer 12 atsaid 28 kc. design frequency.

As is well known to the art, the electrical frequency of the alternatingcurrent power supply (sirch as 60 cycles per second) is changed to matchthe mechanical or elastic vibratory frequency of the transducer (28,000cycles per second in this example, as aforesaid).

The member 18 is preferably semi-flexible and can be curved withincertain limits established by the acoustic characteristics to facilitatemanipulation. Preferably, the curvature of the member 18 has a bendra'dius which is at least x/4 wherein X is the wavelength of thematerial of member 18. The reason for this limitation on the bend radiusis set forth rnore clearly in Patent 3,166,840.

'A coolant fluid may be introduced through conduit 24 and passageway 2].to cop] the member 18, to irrigate tis sue in the vicinity of the tip20, and flush away any micron sized particles resulting from decimationof placques. A low molecular weight dextran solution at a temperature offrom about ambient temperature to body temperature may be pumped throughthe system at low pressure. The solution exits through the tip 20. Themicron sized particles of the placques result from the physical effectof the vibrating catheter tip 20 upon calcified atheromata.

Sterilization of the catheter can be accomplished utilizing conventionalsterilization equipment. If desired, the member 18 may be provided withremovable tips which can be disposable. In order to facilitatesterilization or autoclaving, and simultaneously facilitate manipulationof the catheter with minimum power losses, a force-insensitive mount 15is provided. One end of mount 15 is metallurgically joined to thecoupling member 14. The other end of mount 15 is free. The mount 15 isprovided with a radially outwardly directed flange 17. Flange 17 isjoined to a housing 25 with a waterproof joint. Housing 25 mayconstitute a handle and is preferably of sufiicient length so as toencase the transducer 12 as shown. Suitable plug-in connections 27, 27'can be provided hermetically sealed to the housing 25 for electricallyconnecting to the coils 11 and 13, and to facilitate autoclaving thecatheter.

A force-insensitive mount may comprise a sleeve such as the described inUS. Patents 2,891,178; 2,891,179; and

2,891,180. The disclosures of such patents are incorporated herein byreference. Such a mount facilitates the application of force necessaryto insert the catheter into a cavity, artery, or the like. The sleeve ismade from a metal such as steel or any other suitable resonant materialand has a length equal to a single one-half wavelength. The sleevesurrounds 'the coupler 14 and is concentric therewith and spacedtherefrom.

The flange 17 is spaced from the free end of mount 15 by an acousticaldistance corresponding to one-quarter wavelength according to theproperties of the mount and the desired frequency of operation. Themount 15 when so constructed .will cause a true node of vibratory energyto be developed in the flange 17 so that no vibratory energy will betransmitted to the housing 25.

The operable usage of the ultrasonic endarterectomy catheter requiresthat a reliable source of vibratory energy be coupled to the working tip20 having a diameter of the order of a millimeter. The members 16 and 18may have a length of around 18 inches. To prevent temperature build-upand thereby minimize thermal damage to the tissue, a cooling system asdescribed above is required.

The vibrational energy generated by the transducer can be coupled to themembers 16 and 18 in several different modes. The first and simplestmode is that of longitudinal vibration, as shown, wherein the particledisplacements occur in a direction parallel to the axis of members 16and 18. A second mode of vibration is that of lateral or transversevibration wherein particle displacements occur in a direction normal tothe axis of members 16 and 18. This results in an excursion of the tip20 parallel to the plane of the end face thereof. Other more complicatedmodes including torsional vibration wherein the system oscillatesperiodically in torsion about its own axis, or a radial vibrationwherein the end tip 20 periodically ex= pands and contracts radially maybe utilized.

The exact mechanism by which the placques of the calcified atheromataare destroyed is not well understood. The nature of the mechanism willdepend in part on the physical characteristics of the vibrating tip.Several tip geometries may be employed where desired: In FIGURE 1, thegeometry of the removable tip 20 is a square edge. As shown more clearlyin FIGURE 2, the tip 20 remov= ably mounted on a coupling member 18' mayhave a chisel edge defined by an internal beveled surface 26. In FIGURE2, the beveled surface 26 provides a sharp cut ting edge at theperiphery.

A third type of tip is illustrated in FIGURE 3. Tip 20' removablymounted on coupling member 18" is in 53 bulbous form, The bulb 28 may beeither metal or plastic. The purpose of bulb 28 is to provide a morepositive contact between the working surface of the catheter and thetissue being treated. The surface of bulb 28 may have an abrasivecharacter. The tips of FIGURES 2 and 3 may be substituted for the tip20' in FIGURE 1.

The method steps and conditions for practicing the present invention fortreatment of disease or other conditions for therapeutic purposes isconsidered to be suf ficiently known to those skilled in the art so asnot to require a detailed explanation. Using the known principle ofoxygen in solution, at 3 atmospheres positive pressure ischemia inducedby introducing the catheter by way of the coronary ostia can beprevented. The flow of coolant, such as low molecular weight dextran,can replace oxygenated blood for long periods and prevent a means ofoxygenation to the myocardium.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims rather thanto the foregoing specification as indicating the scope of the invention,

It is claimed:

1. A catheter comprising a transducer means for gen erating vibratoryenergy, a resonant coupling member having one end connected to saidtransducer and a tip at its other end. the end of said tip being at ananti-node on said member, said member having an acoustical length of awhole number multiple of one-half wavelength in the material of which itis made at the frequency of said transducer means, and said member beingpartially hol= low with the hollow portion beginning at said tip,whereby a liquid for cooling said member may be pumped through saidportion for discharge through said tip.

2. A catheter in accordance with claim 1 including a housing, saidmember being hermetically sealed to said housing with said transducermeans disposed within said housing.

3. A catheter in accordance with claim 1 wherein said 6 transducer meansis axially coupled to said member for vibrating said member in adirection corresponding to the longitudinal axis of said member.

4. A catheter in accordance with claim 1 wherein said tip has an endface which is substantially perpendicular to the longitudinal axis ofsaid member. F

5. A catheter in accordance with claim 1 wherein said tip is bulbous.

6. A catheter in accordance with claim 1 wherein said tip has aninternal beveled face providing a sharp-edge at the periphery of thetip.

7. A catheter in accordance with claim 1 wherein said coupling memberhas a length of approximately 18 inches and a diameter along asubstantial length thereof beginning at the tip of approximately 1millimeter.

8. A method comprising the steps of transmitting acoustical vibratoryenergy from a transducer means through a resonant coupling member atleast a portion of which is hollow beginning from a tip end of saidcoupling member designed to have an anti-node at the end face of thetip, introducing a coolant through said portion for dis-' charge throughsaid tip, and transmitting the vibratory energy from the tip to a livinganimal by contacting the portion of the animal with said tip.

References Cited UNITED STATES PATENTS 2,230,997 2/1941 Chambers et al.2,407,690 9/1946 Southworth. 3,358,677 12/1967 Sheldon 128-24 FOREIGNPATENTS 540,428 4/1922 France. 991,494 6/ 1951 France.

L. W. TRAPP, Primary Examiner.

US. Cl. X.R. HS-24, 348

